I'm liking the new Bitcoinica UI. But, as someone who is not very experienced with Forex trading concepts, it seems to me the interface is unnecessarily complex. Let me propose an alternative, simpler model; I'd love to hear from those more experienced in trading interfaces why I'm wrong.
Suppose Bitcoinica displayed only:
- Your $ account value.
- Your BTC account value.
Every time I "trade", one account loses some value, while the other gains. Bitcoinica could lose the concept of an "open position". A margin call could come into play if my total account value ($ + BTC) becomes less that a fixed percentage (say, 20%) of my LONG account balance.
An example:
- Suppose BTCUSD = $2.50
- I send 100 BTC to Bitcoinica ($ = 0, BTC = 100, Net Value = $250)
- I buy 100 BTC at $2.50 ($ = -$250, BTC = 200, Net Value = $500 - $250 = $250 => 50% of LONG)
- BTCUSD decreases to $2 ($ = -$250, BTC = 200, Net Value = $400 - $250 = $150 => 37% of LONG)
- BTCUSD decreases to $1.50 ($ = -$250, BTC = 200, Net Value = $300 - $250 = $50 => 16% of LONG)
- Bitcoica force liquidates 166.67 BTC @ $1.50 ($ = 0, BTC = 33.33, Net Value = $50)
I can grok what is happening much easier with this system. There is no need for Open Positions separate from my Currency Accounts, and it's much easier to see if I am truly LONG or SHORT which currency (and by how much).
Thoughts?
, insult of the day. 
